Bust A Move Doesn’t Have To Be Such A Grind

December 15, 2018 by No comments

PC gamers have the benefit of the mouse and keyboard, which are highly flexible when it comes to input devices for gaming. What’s more, the freedom of the platform means that it’s easy to whip up whatever mad controller you can dream of to best suit the games you’re playing. Enter [Tom Tilley] with the aptly-named Hipster Game Controller.

Yes, this is a controller made out of a coffee grinder. The hand-crank setup makes it perfect for imitating the game board in that puzzle classic, Bust-A-Move. [Tom] interfaces the controller in a perfectly hacky way – the scroll wheel from a mouse is removed from the case and zip tied to the shaft of the grinder, allowing the rotation of the grinder to turn the wheel. The mouse wheel is then mapped as the aim control in the game – it really is that simple. An arcade button is also fitted into a mug and wired into the left mouse button to act as the trigger.

[Tom] notes that while you can fill the grinder up while you play, it makes playing the game very hard work. It’s a hacky build to show that sometimes, you don’t need a microcontroller and lines of code – just a mouse, some wire, and a healthy dose of ingenuity.

And, as it turns out, [Tom]’s been quite the Bust-a-Move fan for a few years now. Video after the break.

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Reflex Trainer Puts Athletes To The Test

December 15, 2018 by No comments

Being a top athlete in this modern age is a full-time job. No longer do athletes simply practice at their nominated sport of choice. They undergo strength training, full nutritional programs, cardio, and even reflex training.

Reflex training involves a series of nodes that an athlete must identify when lit up, and touch them to switch them off. By triggering them in a fast sequence, the athlete must work hard to both identify the lit node and then move to switch it off. TrainerLights is just such a system, built around the NodeMCU platform.

The system consists of a minimum of four lights – one acting as a server, the others as nodes. The lights each contain a nodeMCU board which communicates over WiFi, while the server has an additional board – acting as a WiFi hotspot that controls the system.

With the lights switched on, the coach connects to the server with a smartphone, and configures the lighting sequence and timings depending on the desired excercise regime. The server then communicates with the lighting nodes, which light their LEDs  at specified intervals. The athlete must clear the lights by swiping at the nodes, which detect the athlete’s hand via an ultrasonic proximity sensor. The sensitivity is configurable, to allow the system to trigger from a distant wave or a direct touch from the athlete. This allows a variety of training uses, from tennis to taekwondo.

With a 3D printed case and parts readily available from any good maker supplier, it’s a project you could tackle in a weekend to add to your own training regime.

We see plenty of athletic hacks in these parts – like this line-following robot for training sprinters. Video after the break.

[Thanks to Baldpower for the tip!]

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Build Your Own Anechoic Chamber

December 14, 2018 by No comments

For professional-level sound recording, you’ll need professional-level equipment. Microphones and mixing gear are the obvious necessities, as well as a good computer with the right software on it. But once you have those things covered, you’ll also need a place to record. Without a good acoustic space, you’ll have all kinds of reflections and artefacts in your sound recordings, and if you can’t rent a studio you can always build your anechoic chamber.

While it is possible to carpet the walls of a room or randomly glue egg crate foam to your walls, [Tech Ingredients] tests some homemade panels of various shapes, sizes, and materials against commercially available solutions. To do this he uses a special enclosed speaker pointed at the material, and a microphone to measure the sound reflections. The tests show promising results for the homemade acoustic-absorbing panels, at a fraction of the cost of ready-made panels.

From there, we are shown how to make and assemble these panels in order to get the best performance from them. When dealing with acoustics, even the glue used to hold everything together can change the properties of the materials. We also see a few other cost saving methods in construction that can help when building the panels themselves as well. And, while this build focuses on acoustic anechoic chambers, don’t forget that there are anechoic chambers for electromagnetic radiation that use the same principles as well.

Thanks to [jafinch78] for the tip!

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A Lecture By A Fun Guy

December 14, 2018 by 5 Comments

Many people hear “fungus” and think of mushrooms. This is akin to hearing “trees” and thinking of apples. Fungus makes up 2% of earth’s total biomass or 10% of the non-plant biomass, and ranges from the deadly to the delicious. This lecture by [Justin Atkin] of [The Thought Emporium] is slightly shorter than a college class period but is like a whole semester’s worth of tidbits, and the lab section is about growing something (potentially) edible rather than a mere demonstration. The video can also be found below the break.

Let’s start with the lab where we learn to grow fungus in a mason jar on purpose for a change. The ingredient list is simple.

  • 2 parts vermiculite
  • 1 part brown rice flour
  • 1 part water
  • Spore syringe

Combine, sterilize, cool, inoculate, and wait. We get distracted when cool things are happening so shopping around for these items was definitely hampered by listening to the lecture portion of the video.

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Lessons Learned From A 1-Day RTL-SDR Enclosure Project

December 14, 2018 by 1 Comment

[ByTechLab] needed an enclosure for his R820T2 based RTL-SDR, which sports an SMA connector. Resolving to design and 3D print one in less than a day, he learned a few things about practical design for 3D printing and shared them online along with his CAD files.

The RTL-SDR is a family of economical software defined radio receivers, and [ByTechLab]’s’ enclosure (CAD files available on GrabCAD and STL on Thingiverse) is specific to his model. However, the lessons he learned are applicable to enclosure design in general, and a few of them specifically apply to 3D printing.

He started by making a basic model of the PCB and being sure to include all large components. With that, he could model the right voids inside the enclosure to ensure a minimum of wasted space. The PCB lacks any sort of mounting holes, so the model was also useful to choose where to place some tabs to hold the PCB in place. That took care of the enclosure design, but it also pays to be mindful of the manufacturing method so as to play to its strengths. For FDM 3D printing, that means most curved shapes and rounded edges are trivial. It also means that the biggest favor you can do yourself is to design parts so that they can be printed in a stable orientation without any supports.

This may be nothing that an experienced 3D printer and modeler doesn’t already know, but everyone is a novice at some point and learning from others’ experiences can be a real timesaver. For the more experienced, we covered a somewhat more in-depth guide to practical 3D printed enclosure design.

[ByTechLab]’s desire for a custom enclosure was partly because RTL-SDR devices come in many shapes and sizes, as you can see in this review of 19 different units (of which only 14 actually worked.)

Vintage Plotter Turned Fruit Spectrometer

December 14, 2018 by 8 Comments

Fruit can be a tricky thing: if you buy it ripe you’ll be racing against time to eat the pieces before they turn into a mushy mess, but if you buy the ones which are a bit before their prime it’s not always easy to tell when they’re ready to eat. Do you smell it? Squeeze it? Toss it on the counter to see if it bounces? In the end you forget about them and they go bad anyway. That’s why here at Hackaday we sustain ourselves with only collected rainwater and thermo-stabilized military rations.

But thankfully Cornell students [Christina Chang], [Michelle Feng], and [Russell Silva] have come up with a delightfully high-tech solution to this decidedly low-tech problem. Rather than rely on human senses to determine when a counter full of fruit has ripened, they propose an automated system which uses a motorized spectrometer to scan an arrangement of fruit. The device measures the fruit’s reflectance at 678 nm, which can be used to determine the surface concentration of chlorophyll-a; a prime indicator of ripeness.

If that sounds a bit above your pay grade, don’t worry. The students were able to build a functional prototype using a 1980’s era plotter, a Raspberry Pi, and a low-cost AS7263 NIR spectral sensor from SparkFun which just so happens to have a peak responsivity of 680 nm. The scanning is performed by a PIC32MX250F128B development board with an attached TFT LCD display so the results can be easily viewed. The Raspberry Pi is used in conjunction with a Adafruit PCA9685 I2C PWM driver to control the plotter’s stepper motors. The scanning and motor control could be done with the PIC32 alone, but to save time the students decided to use the Raspberry Pi to command the PCA9685 as that was what the documentation and software was readily available for.

To perform a scan, the stepper motors home the AS7263 sensor module, and then passes it under the fruit which is laying on a clear acrylic sheet. Moving the length of the acrylic sheet, the sensor is able to scan not only multiple pieces of fruit but the entirety of each piece; allowing it to determine for example if a section of a banana has already turned. The relative ripeness of the fruit is displayed to the user on the LCD display as a heatmap: the brighter the color the more ripe it is.

At the end of their paper, [Christina], [Michelle], and [Russell] note that while the scanner worked well there’s still room for improvement. A more scientific approach to calculating how ripe each fruit is would make the device more accurate and take out the guess work on the part of the end user, and issues with darker colored fruit could potentially be resolved with additional calibration.

While a spectrometer might sound like the kind of equipment that only exists in multi-million dollar research laboratories, we occasionally see projects like this which make the technology much more accessible. This year we saw a compact spectrometer in the Hackaday Prize, and going a bit farther back in time we even featured a roundup of some of the most impressive spectrometer builds on Hackaday.io.

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Arduino-Powered Rocket Test Stand

December 14, 2018 by 6 Comments

If you’re into amateur rocketry, you pretty quickly outgrow the dinky little Estes motors that they sell in the toy stores. Many hobbyists move on to building their own homebrew solid rocket motors and experimenting with propellant mixtures, but it’s difficult to know if you’re on the right track unless you have a way to quantify the thrust you’re getting. [ElementalMaker] decided he’d finally hit the point where he needed to put together a low-cost test stand for his motors, and luckily for us decided to document the process and the results.

The heart of the stand is a common load cell (the sort of thing you’d find in a digital scale) coupled with a HX711 amplifier board mounted between two plates, with a small section of vertical PVC pipe attached to the topmost plate to serve as a motor mount. This configuration is capable of measuring up to 10 kilograms with an 80Hz sample rate, which is critically important as these type of rocket motors only burn for a few seconds to begin with. The sensor produces hundreds of data points during the short duration of the burn, which is perfect for graphing the motor’s thrust curve over time.

Given such a small window in which to make measurements, [ElementalMaker] didn’t want to leave anything to chance. So rather than manually igniting the motor and triggering the data collection, the stand’s onboard Arduino does both automatically. Pressing the red button on the stand starts a countdown procedure complete with flashing LED, after which a relay is used to energize a nichrome wire “electronic match” stuck inside the motor.

In the video after the break you can see that [ElementalMaker] initially had some trouble getting the Arduino to fire off the igniter, and eventually tracked the issue down to an overabundance of current that was blowing the nichrome wire too fast. Swapping out the big lead acid battery he was originally using with a simple 9V battery solved the problem, and afterwards his first test burns on the stand were complete successes.

If model rockets are your kind of thing, we’ve got plenty of content here to keep you busy. In the past we’ve covered building your own solid rocket motors as well as the electronic igniters to fire them off, and even a wireless test stand that lets you get a bit farther from the action at T-0.

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